Refrigeration method and apparatus utilizing carbon dioxide in a solvent



May 16, 1950 M. s. PLEssET ETAL 2,507,856

REFRIGERATION METHOD AND APPARATUS UTILIZING CARBON. DIOXIDE IN A SOLVENT Filed Oct. 13, 1945 Patented May 16, `195() REFRIGERATIONLIETHODAND APPARATUS UTILIZING CARBON DIOXIDE 4IN A SOL- VENT Milton Si Flessen -tosemead, and Thomas N. Floyd, Manhattan Beach, Clif'f., a'ssignors to Keller Engineering' Company,

Calif., a copartnership Application October `13, 1945,` Serial No. 622,158

'l1-Claims'. 1

This invention relates to a refrigeration methd and apparatus. It is the general object of the present invention to provide a means fora method and apparatus for refrigeration, by means of which low refrigeration temperatures may be obtained in a very simple apparatus operated at a low cost.

There is at present considerable demand for a simple and economical method and apparatus for refrigeration for use in cooling storage chambers, cold boxes, cold rooms, altitude chambers, cargoco'mpartments, or experimental equipment at low temperatures.

Solid carbon dioxide has heretofore been einployed in some cases for lowering the temperature for cold boxes, etc., but the sublimation temperature of carbon dioxide is about 110 F., and in many cases it is desired to operate at temperatures nearly as low, or lower than, the sublimation temperature of carbon dioxide.

In accordance with the method and apparatus of the present invention, the refrigerant employed consists of solid carbon dioxide in contact with a solvent therefor forming a liquid refrigerant phase, which liquid refrigerant phase is maintained at a temperature below the sublimation temperature of solid carbon dioxide. The lowering of the temperatureof the refrige'rant below the sublimation temperature-is accomplished by means of agitating the mixed liquid and solid phases with a gas, such asai'r. We have found that in this manner the temperature of the liuuid. phase of the refrigerant may be readily maintained as low as 150 F., and believe that temperatures as low as 200 F. may be maintained, if desired.

In the method and apparatus of the present invention, the refrigerant thus reduced in temperature to below the sublimation temperature of carbon dioxide may be circulated by means of a pump through a heat exchanger for exchanging heat with the air of the storage chamber, etc., and then the refrigerant returned and sprayed through a perforated header in the sublimation chamber for the release of any carbon dioxide gas which has come out of the solution due to energy transfer. Such carbon dioxide gas together with the air or other gas used in agitating the refrigerant in the chamber, are vented to the atmosphere.

The method and apparatus of the present invention will be more fully understood from the following description of the preferred form or example of the method and apparatus embodying the invention. For that purpose, we have Los Angeles,

hereafterdescribedra preferrdforni of thefapalatusarid method 0f th'pl's'et invention' iii connection with the accompanying drawing.

In theV drawing theV figure represents a Soniewhat diagrammatic prspective 'View of'fan appa'- ratus through the method of performing the'process of the present invention, lpart vof the appae ratus being indicated in section.

Referring to the drawing, theapparatu's iii-- cludes asublimation chainb'e'r'i' which may-beni any desirable form capable of holding 'a supply of solvent of carbon dioxide and alsoextra car= bon dioxide. IThe sublimation chamber I preferably well insulated-,as indicated by the-'walls' 2, in -order to prevent heat leakage from the atmosphere through the wallsA of the chamber.

` There is provided an opening Vor door means of which the solvent and solid carbon dioxide are introduced into'the chamber. A vventii's-i'di= cated for venting carbon dioxide'and gas tothe atmosphere. l

While in some cases inthe usev of-the 'process' and-apparatus of the present invention the-'sublimation chamber I it'self rnay besedas" aba-th; refrigerant, normally in the use of theprocess and apparatus of' the present 'inventlonthe subev limation chamberV is`'connected*toV `a heat exchanger, such as isy indicatedati. Thefheat exchanger `5l may be of any usualor-prferredfy type, or may be either a forced or' of trie-free convection type including any usual or preferred defrosting -ineans-andtlie lu'a'at exchanger is intion chamber I by means of an inlet line 6, including a pump 1. Within the sublimation chamber I the inlet 6 is shown as connected to a perforated header 8, preferably located in the lower part of the chamber and protected by a hood 9 which serves to prevent damage to the header 8 from solid carbon dioxide dropped into the sublimation chamber I.

The outlet from the heat exchanger 5 is connect'ed with the return line I0 to a perforated header II by means of which the returning refrigerant is sprayed into the sublimation chamber, thereby assisting in the liberation from the solvent of any carbon dioxide gas formed due to the energy transfer in the heat exchanger 5.

The apparatus also includes an agitation system, which agitation system consists of one or more perforated headers I2 positioned Within the sublimation chamber and preferably positioned adjacent where the bricks of carbon dioxide may be conveniently placed. The perforated header is indicated as connected to a source of supply of air or gas, such as the line I4. The line M preferably leads through a suitable drier I5. It is preferable in the method of the present invention that the gas or air drawn into the sublimation chamber be dry as otherwise the solvent in the sublimation chamber will become progressively diluted with water.

It will be understood that in practice the gas is introduced into the chamber under pressure, such as from 10 to 100 lbs. per square inch, although it is obvious that any means of effecting iiow of the gas through the chamber may be employed.

In the present invention, any usual or Wellknown solvent for carbon dioxide may be employed. Solvents for carbon dioxide include generally all alcohols, ketones, and esters. We have generally employed methanol or acetone as the two solvents and believe them to be the most economical solvents to employ, although obviously other solvents such as ethanol, methyl acetate, or ethyl acetate may be substituted therefor. The temperature maintained in the refrigeration system is of course governed by the demands on the heat exchanger 5 and also the rate of introduction of air, or other gas, into the sublimation chamber.

Throughout the use of the method and apparatus of the present invention, carbon dioxide in solvent form in excess of that which is soluble in the liquid refrigerant should be maintained in the sublimation chamber. By introducing suiicient air or other gas to carry rapidly from such blocks of dry ice the carbon dioxide vapors, temperature substantially below the sublimation temperature of carbon dioxide may be established and maintained in practice.

The method and apparatus of the present invention provides a very simple, economical and efficient method for maintaining storage chambers, cold boxes, cold rooms, altitude chambers, etc., at low temperatures.

While the particular form of the apparatus herein described is well adapted to carry out the objects of the present invention, it is to be understood that various modifications and changes may be made, and this invention is not limited to the particular form described, but includes all such modifications and changes as come within the scope of the following claims.

We claim:

1. A refrigerant method, in which a supply of refrigerant is maintained, which refrigerant con- 4 sists of solid carbon dioxide in contact with a liquid phase consisting of a solvent therefor and dissolved carbon dioxide, said phases being under agitation by a gas other than carbon dioxide, and circulating the liquid phase from the supply to a heat exchange zone and returning the refrigerant from the heat exchange zone to the source of supply.

2. A refrigerating process in which a liquid refrigerant is passed from a source of supply through a heat exchange zone and back into said source of supply, such source of supply consisting of solid carbon dioxide and a solvent for carbon dioxide having dissolved carbon dioxide, said solvent being in contact With said solid carbon dioxide, and agitating said source of supply with a gas other than carbon dioxide for maintaining the temperature of the solvent containing dissolved carbon dioxide below the sublimation temperature of carbon dioxide.

3. A refrigerating apparatus which consists of a chamber for holding an admixture of solid carbon dioxide and a solvent therefor, means for distributing a gas into the aforesaid mixture for agitation of the same, a heat exchanger and means for withdrawing the liquid phase from said chamber and circulating the same through the heat exchanger and back into said chamber.

4. A refrigerating apparatus which consists of a chamber for holding an admixture of solid carbon dioxide and a solvent therefor, means for distributing a gas into the aforesaid mixture for agitation of the same, a perforated intake pipe for withdrawing liquid refrigerant from said chamber, a hood covering said intake pipe, a heat exchanger and means for circulating liquid refrigerant from said intake pipe to the heat exchanger and back into said chamber.

NHLTON S. PLESSET. THOMAS N. FLOYD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

1. A REFRIGERANT METHOD, IN WHICH A SUPPLY OF REFRIGERANT IS MAINTAINED, WHICH REFRIGERANT CONSISTS OF SOLID CARBON DIOXIDE IN CONTACT WITH A LIQUIP PHASE CONSISTING OF A SOLVENT THEREFOR AND DISSOLVED CARBON DIOXIDE, SAID PHASES BEING UNDER AGITATION BY A GAS OTHER THAN CARBON DIOXIDE, AND CIRCULATING THE LIQUID PHASE FROM THE SUPPLY TO A HEAT EXCHANGE ZONE AND RETURNING THE REFRIGERANT FROM THE HEAT EXCHANGE ZONE TO THE SOURCE OF SUPPLY. 